The present invention relates to a sheet feeder.
Conventional sheet feeders are disclosed in JP-A-2005-292236 and JP-A-2006-176321. The sheet feeder has a housing, a sheet feed cassette, a pressure plate, and a pressure mechanism.
The housing has a cassette housing part. The cassette housing part is recessed horizontally from the front surface toward the depth direction. Further, a pick-up roller that is driven rotationally about a horizontal axis perpendicular to the depth direction is provided in the upper part at the front surface side within an opening of the cassette housing part.
The sheet feed cassette has a holding chamber having an open top for storing stacked sheets of paper, and can be housed within the cassette housing part and drawn from the cassette housing part.
The pressure plate is provided pivotably about a pivot in parallel with the horizontal axis so as to be inclined downwardly toward the depth direction of the sheet feed cassette.
The pressure mechanism presses sheets of paper against the pick-up roller by increasing the angle of inclination of the pressure plate when the sheet feed cassette is pushed into the cassette housing part.
The conventional sheet feeder having such a configuration is applied to an image forming apparatus such as an electrophotographic printer. As described below, the sheets of paper are loaded in the sheet feed cassette and the sheets of paper are fed to the image forming apparatus.
First, a user draws the sheet feed cassette from the cassette housing part of the housing to draw the sheet feed cassette by the length more than the length of sheets in the depth direction. Concurrently, the pressure plate is horizontal at the reduced angle of inclination.
Next, the user stacks sheets of paper from above the holding chamber of the sheet feed cassette, and then, inserts the sheet feed cassette from the front of the housing to the depth direction to make the sheet feed cassette housed in the cassette housing part.
In this manner, when the sheet feed cassette is pushed into the cassette housing part, the pressure mechanism increases the angle of inclination of the pressure plate and presses the sheets of paper against the pick-up roller. Thereby, the loading of sheets of paper in the sheet feeder is completed. Further, in the sheet feeder, when the sheets of paper are fed to the image forming apparatus, the pick-up roller rotates and associated components such as rollers and guides provided around work in conjunction with the pick-up roller. Thus, the sheets of paper can be fed one by one to the image forming apparatus from the upper part of the front surface side within the opening.
By the way, image forming apparatuses such as printers have been recently downsized and often placed near the work areas on the desks or the like. Accordingly, it is desired for the image forming apparatus to occupy the smaller space so as not to reduce the work area. On this account, it is also desired for the above described conventional sheet feeder to occupy the smaller space.
However, in the above described conventional sheet feeder, it has been difficult to make the occupied space smaller at the front surface side of the sheet feeder because the sheet feed cassette must be drawn by the length more than the length of sheets in the depth direction when the sheets of paper are loaded in the sheet feed cassette.